<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        div{
            /*块级元素*/
            width: 200px;
            height: 200px;
            display: block;
            border: 5px solid #f00;
        }
        span{
            width: 200px;
            height: 200px;
            display: block;
            background: #ff0000;
        }
        button,input{
            /*既不是行内元素,也不是块级元素,是行内块元素*/
            width: 200px;
            height: 200px;
        }
        .d2{
            display: none;
        }
    </style>
</head>
<body>
    <div class="d1"></div>
    <div class="d2"></div>
    <div class="d3"></div>
    <hr>
    <span>123456789</span>
    <span>123456789</span>
    <span>123456789</span>
    <input type="text">
    <input type="text">
    <input type="text">
    <button>lkp</button>
</body>
</html>